"I am really excited about rejoining Everton," said Lukaku. "I had a fantastic experience last season and a great relationship with the manager, the chairman, the staff, the players and the fans. I can't wait to get started again and I'm looking forward to a successful season."

Everton's previous club-record signing was £15m midfielder Marouane Fellaini, whom they signed from Standard Liege in September 2008 before selling to Manchester United for £27.5m last summer.

Manager Roberto Martinez added: "Welcoming Romelu Lukaku back to Everton on a permanent basis is the news that all Evertonians wanted to hear.

"We know that Romelu is still a young man and the potential that he has is quite unique, and we are desperate to see him enjoying his football and to watch him grow as footballer in the years to come.

"The arrival of Rom is more than just a signing, it's the fruition of a lot of hard work to get the player we wanted. This is a big moment for Everton's history and the perfect way of getting the squad ready for the start of the season."

Earlier on Wednesday, Lukaku posted a picture of himself on Twitter seated on a private jet, along with the caption: "Time to write a new chapter."